Internal damping of stock arm, experiences?

[Virak]

Due to space restrictions, my SL-1610Mk2 will be the front end in my livingrom for a while. There's simply no room for the big ones.

I already have the KAB silicone dampener (great mod, IMO) and the resonance cap, but since I need to replace the RCA's, I thought I might as well look into internal damping of the arm while I'm at it.

KAB has been internally damping arms with cotton, and is now also offering a rubber lining ( https://www.kabusa.com/ ), so I was wondering if any of you AOS'ers have experimented with this type of mods? External shrinktubing and such is out of the question, I want a clean look.

[Dubster68]

I updated my original SL1210 arm with very good results. I used industrial foam ear plugs. These roll thin in your fingers and slowly expand. This gives you time to insert into the tone arm tube. Also the rear weight stub can be removed and packed in the same way. I also rewired from the headshell right through to RCA plugs in one run with an Incognito kit. Whilst this was done I shrink wrapped the tone arm. All these tweets gave a massive improvement over the standard arm. I only changed the arm as I got a Jelco at a good price. Completing these mods I think you will hear a big difference in sound.

Good luck

[Ianmac]

I also want to find out if its really necessary to replace the techie arm
Im running with a Goldring cartridge with a 1042 stylus, Silicon damping similar to KAB, Heatshrink on the arm and an underslung counterweight and getting good results.
Before trying any further arm tweaks I have just upgraded my phono pre amp to ensure I have a very good signal path which will not mask any further detailed improvement in PU output.

I want to look at an existing arm filled with foam to dampen it. I intend to use a self expanding foam, similar to that used in the building industry to seal cavity gaps. This can be mixed oneself from two chemicals, the ratio of the mix determines the density of the foam.
My intention is to remove the techie arm and wiring. Remove the front plug and wires. Inset a bendy drinking straw into the arm tube to provide a path for the PU wires. Fill the arm with my mix of foam such that it expands to completely fill the volume between the arm tube inner and the bendy drinking straw. This will adhere to the arm tube inner and, in theory, improve rigidity of the tube and the damping of any " vibration" from the PU assembly or internal resonances.
Reasemble the arm and evaluate.
I also have some carbon fibre tube ready to try an alternative " straight arm " using a two tube coaxial arrangement with the same self expanding foam between inner and outer tube.
There are alternative fillings one could used based on silicon rubber but weight will be an issue

Early days, but Im sure some inexpensive tweaks must exist.
The latest technics decks still appear to use the same bendy arm.

[Cycleallday]

The latest technics decks still appear to use the same bendy arm.

and with excellent results judging by the new 1210 on demo at Bristol (sporting a 2M Black cart).

[Ianmac]

Ive had a look at filling my stock arm with cellfoam. Unfortunately after removing the 2 screws holding the head connector in place the socket refused to pull out of the arm. Attempts to really put some pull on this run the risk of damaging the arm. I found traces of araldite so looks like someone glued it in position at some time in an earlier life.
This was a blessing in disguise. !
I moved forward by building a Carbon fibre arm and a new aluminium head mount, machined from the solid.
For the arm I used a coaxial construction with 10mm outside tube and a 6mm inside tube with cellfoam in between the outer "inside" and inner "outside" diameters. The arm length and head mount were made to match the Technics Baerwald dimensions with the offset at precisely 23.6 degrees.
The prototype is running now on one of my decks with a Goldring 1012 and the results are very promising. Wide, balanced frequency range with none of the "muddiness" I experience with busy multi instrument music using the stock arm in various guises.
IMOP much better than the stock arm so will concentrate on finalising this design
I havent tried a silicon damper yet but will do so in the next week.
Cost so far £20 but dont mention the time Ive spent and self inflicted mistakes Ive made.
As soon as i get time i'll pull together some photos and hopefully test measurements from my test disc

Firefox is telling me not to log into the site due to security issues??

[alphaGT]

Perhaps a test run with the foam ear plugs might make sense? If you use the chemical foam, and then don't like it, it will be very difficult to remove. Too much damping can be too much of a good thing, and dull the sound a bit?


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[dimkasta]

I did try some cotton tubing back when I first re-wired my tonearm. It was pretty loose in there though, not tightly stuffed. I also tried some thick heatshrink. In both cases I remember the change being very small. Almost borderline psychological. I must say though that my sl1200 back then was pretty much stock, so I probably should do some more testing now that the TT is much improved.

I also briefly worked on a carbon tonearm, but had a problem building a cheap and accurate enough headshell for it. I now have easy access to a cnc laser cutter, so I will probably get back to it at some point. I also want to try the nice and simple linear and unipivot designs out there. But they are low in my long todo list.

[Ianmac]

Sure using chemical foam is final. Further change is a new Carbon tube and rebuild, not a problem, I have enough tube and want to experiment and measure using an aluminium inner tube to see if there is any difference in electrical /electromagnetic screening of the PU wires from the techie motor as the PU travels from outer to inner
Im certainly not dulling the sound.
I have two decks, one with the std arm + heatshrink + KAB type damper the other with my Carbon fibre arm so can do instant comparisons. At the moment the CF arm is by far the best but I will progress just a little more before drawing a conclusion

Perhaps a test run with the foam ear plugs might make sense? If you use the chemical foam, and then don't like it, it will be very difficult to remove. Too much damping can be too much of a good thing, and dull the sound a bit?


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[alphaGT]

Sounds like you've got everything under control. Just remember the scientific method, only one change at a time, so you'll know exactly what caused each change.


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[vs_jk]

With the variability in systems, results seem to vary. In my system, heatshrinking the SL1210Mk2 stock tonearm made a major improvement in sound. Plus that was when my turntable was still stock. It is fairly thick heatshrink that is shrunk on very snug. This turntable is the source component in my headphone based system so it's probably easier to hear differences in sound.

I've been giving some thought to rewiring the arm and adding damping with some cotton on the inside. So, will be following this thread closely to read the group's impressions of this mod. Although, I'm very skeptical of improvements attributed to the wiring.